While the Michigan defense returns eight starters, there are significant holes to fill up front. That is ominous news for a program hoping to pull off an upset iin the season opener against an Alabama team with perhaps the nation's top offensive line.

The Michigan vs. Alabama showdown (Sept. 1 at Cowboys Stadium in Dallas) is shaping up to be the most-anticipated non-conference game in college football this fall.

The early line heavily favors the Crimson Tide, and deservedly so; 'Bama is the defending national champion and boasts, arguably, the greatest collection of talent of any team in the country. The Wolverines, on the other hand, are in year two of Brady Hoke's resurrection program, and even though they went 11-2 in 2011, beating Virginia Tech in the Sugar Bowl, their overall talent isn't yet where it needs to be to compete regularly for national championships.

But on any given day, any team can win, and the Maize and Blue, with senior quarterback Denard Robinson running the offense, believe strongly they can knock off the reigning champions.

To do so, Michigan's defensive line, with three new starters, will have to at least hold fort with an Alabama offensive line returning four players who started at least nine games in 2011 - a unit ranked the nation's best by preseason magazines Athlon, Lindy's and Phil Steele's.

Outland Trophy winner Barrett Jones, who is moving from left tackle to center to shore up one of the Tide's potential weaknesses, senior left guard Chance Warmack and junior right tackle D.J. Fluker, meanwhile, have been named preseason All-Americans by a variety of the forecasting publications.

Michigan counters with just one returning starter, senior Craig Roh, who is moving from the weakside (rush end) position to the strongside defensive end position, and three first-time starters, including senior nose tackle William Campbell, who after three years of minimal impact is looking to live up to his five-star billing in the Class of 2009.

"Will's play this season is crucial because every great defense needs to have a great nose tackle. Period," defensive line coach Jerry Montgomery said. "If you're weak in the middle, you're a weak defense. If you're strong in the middle, you have the chance to be a great defense. So he's critical."

The 6-foot-5 Campbell, who reports he's down to 315 pounds, has played in 38 career contests, including 27 along the defensive line. He possesses All-America potential, and always has, but his technique comes and goes, and his dedication to staying low has also waned.

"If he can consistently play with great pad level, which he has shown at times, he'll be just as good as anybody in our conference, in the country, and as good as we need him to be," Montgomery said. "But he has to bend, and be conscious of it, and play technique-sound football to be a great football player."

Campbell emerged as a leader of the entire defense in the spring, and has continued to push his teammates this summer. He's cognizant of his need to perform every snap he's on the field, knowing if he doesn't get the job done, the entire defense will suffer.

"With the coaching we have, and the opportunity, it's all on me, and I have no excuse if I don't deliver," Campbell said. "I'm putting in the hours, working really hard on my technique, watching film. I'm going to do everything in my power to have a great senior year."

Campbell is the key to the defensive line fulfilling the expectations necessary for Michigan to compete for a Big Ten championship this season and shut down a Crimson Tide offensive attack growing in confidence with the success of junior quarterback A.J. McCarron and his surrounding cohorts. But one man cannot do it alone.

The Maize and Blue need Roh to be strong against the run. They need junior Jibreel Black, who was Roh's understudy at weakside end last year, to be a playmaker at defensive tackle alongside Campbell. And they need sophomore rush ends Frank Clark and Brennen Beyer to team up for 15-20 sacks and 25-30 tackles for loss, while holding up against the run.

For Michigan to vie for the conference crown, and potentially more, it needs its revamped defensive line to outperform a unit that was the team's best in 2011, with two three-year starters (nose tackle Mike Martin and strongside end Ryan Van Bergen). No easy task, yet defensive coordinator Greg Mattison - one of three coaches, along with Montgomery and Hoke, trained as a defensive line mentor - demands they get the job done. Immediately.

"They don't have a choice," Mattison said. "Our goal is the Rose Bowl, a Big Ten Championship, but we're not OK losing any game on our schedule. It's not OK to lose to Alabama. It's not OK to lose to Notre Dame.

"You do lose games. It happens sometimes. You wish it wouldn't, but you never go into a season thinking it's OK if we lose this game as long as we don't lose these.

"So is it fair to expect that much from them? It doesn't matter,"Mattison continued. "We need those players playing at a high level, and it's our job as coaches to get them ready once we start fall camp. And it's their job to spend the summer getting themselves ready. They understand that. They know who we begin with. They know we open with Alabama."